Wireless sensor networks are used to monitor changes in conditions across an area of interest. Some example applications include medical sensors that are implanted in different parts of the body, security sensors that can detect intrusions at a residence and environmental sensors that measure temperature or the presence of particular gases in an industrial plant.
Generally, a wireless sensor network includes multiple individual sensor nodes that are distributed across an area of interest. Each node includes a sensor that monitors changes in temperature, pressure or other characteristics in the ambient environment. Each node includes a transmitter, which enables it to communicate the sensor data to a coordinator device. The sensor data may be obtained at the coordinator device and used to analyze the environment and make adjustments as appropriate.
In many current sensor networks, each sensor node is powered by a battery. There has been growing interest in the use of energy harvesting sensor devices. An energy harvesting sensor device is a sensor node that uses the ambient environment (e.g., pressure, vibration, light, etc.) to provide the necessary power to support the communication and monitoring operations of the device.